Performance and Emissions of a DI Diesel Engine Operated with LPG and Ignition Improving Additives

This research investigated the performance and emissions of a direct injection (DI) Diesel engine operated on 100% butane liquid petroleum gas (LPG). The LPG has a low cetane number, therefore di-tertiary-butyl peroxide (DTBP) and aliphatic hydrocarbon (AHC) were added to the LPG (100% butane) to enhance cetane number. With the cetane improver, stable Diesel engine operation over a wide range of the engine loads was possible. By changing the concentration of DTBP and AHC several different LPG blended fuels were obtained. In-cylinder visualization was also used in this research to check the combustion behavior. LPG and only AHC blended fuel showed NO_X emission increased compared to Diesel fuel operation. Experimental result showed that the thermal efficiency of LPG powered Diesel engine was comparable to Diesel fuel operation. Exhaust emissions measurements showed that NO_X and smoke could be considerably reduced with the blend of LPG, DTBP and AHC.